The present invention relates generally to air filtration systems, and more particularly provides a self-cleaning, multi-filter air filtration system having structurally improved filter housing and mounting apparatus incorporated therein.
In the art of self-cleaning filter systems, numerous methods have been proposed for mounting cylindrical filter cartridges within the housing portion of the system, and for periodically cleaning such filters during the course of system operation.
In typical systems having filters mounted in the dust-laden air below the housing centerplate, filter mounting means that tend to minimize overall housing height are most desirable. This is conventionally accomplished by providing filter mounts which permit insertion of the various filters directly through the housing sidewalls into a contaminant chamber portion of the housing disposed beneath the centerplate. Such direct entry filter mounting technique is exemplified in U.S. Pat. No. 4,209,310 and U.S. Pat. No. 4,319,897. In the first patent, the filter is secured to the centerplate by means of a drawbar extending through the filter bore and threadingly engaging a retainer web positioned in the center plate opening located directly beneath a filter reverse flushing air valve. In the second patent, the filter incorporates a flange around the clean air flow bore exit, whereby the flanged end is clamped in sealing engagement to the housing centerplate and is aligned with a reverse flushing filter cleaning element.
A variety of problems have typically been encountered with direct entry filter mounting system of the type described. For example, in such conventional systems the entire weight of the suspended filter or filters is borne entirely by the centerplate. Typically, a filter element with 200 square feet of pleated filter media, in an un-cleaned condition, weighs approximately 30 pounds. In the twelve filter example of the second patent, the total filter weight supported by the housing centerplate could reach approximately 360 pounds. This static deflective load on the centerplate is in addition to the deflective load thereon created by internal pressures within the contaminant chamber portion of the housing caused by the flow of particulate-laden air therethrough.
In such conventional systems, particularly when the filters begin to clog with particulate matter, the housing static pressure may rise to the collapse or "burst" strength of the filters. This internal housing pressure may easily reach 5 psig. Accordingly, both the housing walls and the centerplate must typically be designed to withstand these internal pressure variances, and the centerplate, from which a series of relatively heavy filter elements are suspended, must be designed to withstand not only these pressure-induced deflective loads but the filter weight deflection load as well.
Another problem associated with conventional filter housing and mounting apparatus in which the filters are suspended from a large-area centerplate is that the filter elements, and various pieces of their associated suspension mounting hardware, can fall into the hopper section (typically disposed beneath the filter housing) during mounting or removal of the filter elements. Simply stated, if care is not exercised in handling the relatively heavy filter elements, they may easily slip from the installer's outstretched hands and fall, together with some or all of their mounting hardware, into the hopper section below. This, of course, can necessitate the partial disassembly of the filtration system to retrieve the dropped components.
It is accordingly an object of the present invention to provide stucturally improved filter housing and mounting apparatus which eliminates or substantially minimizes above-mentioned and other problems and limitations associated with conventional filter housing and mounting apparatus of the general type described.